How to Prolong the Service Life of Metal Bellows Mechanical Seal?

1. The metal bellows mechanical seal has a wide range of applications

From low temperature to high temperature, from neutral medium to corrosive medium, from low speed to high speed, from ordinary to harsh working conditions can be used. Bellows include rubber bellows and serpentine sleeves, plastic bellows and metal bellows. Rubber bellows and serpentine sleeves are used for low-load mechanical seals as auxiliary seals; plastic bellows are used for mechanical seals of strong corrosive media as auxiliary seals; metal bellows are used for mechanical seals of high-temperature, high-pressure and low-temperature media, which can be used as auxiliary seals, or as elastic element.

2. The method of extending the service life of the metal bellows mechanical seal

Metal bellows should have greater elasticity, strength and rigidity. It can be used in occasions where the pressure reaches 7Mpa. It is suitable for high and low temperature operations. The temperature resistance is -240°C ~ +650°C. The thickness of the film is not more than 0.4mm, which determines that the bellows material should have high corrosion resistance and be used in neutral media. . Since it is difficult for the metal bellows mechanical seal to keep the contact surfaces absolutely parallel, the internal movement of the mechanical seal itself is also normal. This movement is often caused by equipment and installation tolerances, thermal expansion, piping stress, or improper spindle tuning. In order to keep the sealing surfaces mated at all times, the spring acts as a constant adjustment between the mechanical seal and the movable shaft.

When an elastomeric seal is used between a rotating surface and the spindle, the elastomer will move back and forth on the spindle. This repeated friction will wear away the anti-corrosion material on the main shaft, lose the protective coating of the oxide film on the main shaft, and eventually form wear grooves on the friction surface of the main shaft, resulting in fluid leakage from the main shaft. And increased the necessary maintenance workload. Even replace the spindle. To solve this problem, replaceable sleeves are usually installed in the stuffing box. However, the solution to the corrosion and wear problems is to remove the dynamic seals from them.

Today, most major seal manufacturers produce non-corrosive wear seals to prevent corrosive wear on pump parts. The balance of balanced and unbalanced mechanical seals has a significant effect on the sealing pressure at the contact surfaces. This sealing pressure depends on the effective cross-section of the seal itself and the pressure inside the stuffing box. The cross-section on the other side of the rotating surface of the unbalanced seal is fully exposed to the pressure range of the stuffing box. This condition creates higher sealing pressures between the sealing faces, which increases operating temperatures and increases the rate of wear. Under high temperature working conditions or when the liquid is highly corrosive and corrosive, the service life of the metal bellows seal will be greatly shortened. Balanced mechanical seals reduce seal pressure and extend seal life.

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